Install Searchkick
Replace member SQL search with Searchkick's elasticsearch
Remove tests that aren't relevant in a post-elasticsearch world
Remove tests that are only testing different text on a submit button

They seem a bit pointless now we're not comparing to PHP
Add readme note about elasticsearch
Revert "Replace member SQL search with Searchkick's elasticsearch"

This reverts commit da5204d509161e143d6fd416c94cce29a1af14c4.
Make enabling elasticsearch optional and default to off
Use elastic search for member when enabled
Use elasticsearch for policies when enabled
Use elasticsearch for divisions if enabled
Fix typo
Reindex the division when we create a new wiki motion
Only reindex if elasticsearch is enabled
Don't enable searchkick on models if elasticsearch is not enabled

This stops callbacks running (and quietly failing) if we've not chosen
to enable elasticsearch
Merge branch 'search'